Ajax’s Daley Blind collapsed during a pre-season friendly on Tuesday, raising fears over his career following his diagnosis with a heart condition last year.

The former Manchester United defender was diagnosed with heart muscle inflammation after suffering from dizziness during Ajax’s Champions League match against Valencia in December.

Blind, 30, was fitted with a subcutaneous implantable cardioverter defibrillator (S-ICD system) before returning to full training and match action in February. The device constantly monitors and regulates the heart’s rhythm.

However, concern was evident in Amsterdam on Tuesday as Blind’s teammates rushed to his aid as he collapsed to the floor in the closing stages of Ajax’s friendly against Hertha Berlin.

After the match, Ajax boss Erik ten Haag said that Blind was feeling “okay” but would undergo further tests at hospital on Wednesday morning.

Ten Hag said to Dutch TV station Ziggo Sport, “Daley Blind’s ICD went off. He got subbed off straight away and he is feeling OK now, he is feeling fine. We will do research about this now.”

Blind, who began his career with Ajax, spent four years at Old Trafford before returning to his boyhood club in 2018. He has made 68 appearances for the Netherlands, Sky reports.

Ajax are set to start the Dutch Eredivisie season on Sunday, September 13, but Blind’s participation could now be in doubt following his latest health scare